Please note that dynamic tick may affect the accuracy of
timekeeping on some platforms depending on the implementation.
Currently at least OMAP, PXA2xx and SA11x0 platforms are known
to have accurate timekeeping with dynamic tick.

No HZ timer ticks in idle found in arch/s390/Kconfig

Help text

Switches the regular HZ timer off when the system is going idle.
This helps z/VM to detect that the Linux system is idle. VM can
then "swap-out" this guest which reduces memory usage. It also
reduces the overhead of idle systems.